1. Field of the Invention
This invention relates to vitamin C powders prepared by spray drying an aqueous slurry of ascorbic acid and a binder in the presence of an absorbent.
2. Description of the Prior Art
U.S. Pat. No. 3,396,226 relates to compositions which are suitable for direct compression into tablets without prior granulation procedures. The compositions consist of a mixture of (1) from about 60 percent to about 80 percent by weight of ascorbic acid, (2) from about 19 percent to 50 percent by weight of microcrystalline cellulose, and (3) at least one lubricant selected from the group consisting of metallic stearates and other similar compounds. The ascorbic acid has a particle size such that not more than 60 percent by weight thereof is retained on a 100 mesh screen, from about 10 percent to about 50 percent by weight thereof is retained on a 200 mesh screen, and from about 30 to 75 percent by weight thereof is passable through a 200 mesh screen. The compositions described in this patent are prepared by mixing or blending.
One of the problems with this method is that the resulting tablets have high amounts of microcrystalline cellulose and, consequently, low amounts (no more than 80 percent by weight) of ascorbic acid. Furthermore, the process used in making the composition is not a continuous one.
U.S. Pat. No. 3,293,132 describes a continuous process for making a vitamin C powder by spray drying. The process involves spray drying from 75 to 95 parts by weight of ascorbic acid, from 5 to 25 parts by weight of a carbohydrate, and from 0.5 to 5 parts by weight of a filmproducing hydrophilic, organic colloid material such as gelatin, water-soluble derivatives of casein, water-soluble gums, and water-soluble derivatives of cellulose. Although the process is continuous, it has the disadvantage of utilizing a carbohydrate such as a sugar, for example, lactose, sucrose, maltose, glucose, etc., which are not desirable in the vitamin C powder and tablet for nutritional reasons.